Comparative Study of Unbonded Carbon Fiber and Steel Strands in Posttensioned Pier Caps
Publication: Journal of Composites for Construction
Volume 20, Issue 1
Abstract
Carbon fiber strands offer a viable alternative to corrosion-prone steel strands in posttensioning applications. This study focused on a side-by-side comparison of two types of carbon fiber strands with different elastic moduli against steel strands in a scaled model of a typical interior hammerhead pier of the San Antonio Downtown project with two identical cantilever overhangs. Two different strand arrangements were used for posttensioning, with eight and six strands, respectively representing an overdesign and a slight underdesign relative to the factored demand. The model was tested under service and factored flexure and shear loads. The study confirmed the feasibility of using carbon fiber strands in unbonded posttensioning of pier caps. Given the strength-based design of the pier cap, the elastic moduli of different carbon fiber strands did not seem to have affected the serviceability performance with respect to either cracking or deflection. Considering both serviceability and overload conditions, the general performance of the pier cap model under both flexure and shear loading was deemed acceptable using either type of carbon fiber strands, and quite comparable to that of steel strands.
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Acknowledgments
This study was sponsored by the Florida Department of Transportation under the supervision of Mr. William Potter as project manager. The support of Titan America for providing the concrete, C&C Concrete Pumping for providing the concrete pumping, Mo Steel Fabricator & Erector for the steel frame fabrication, Mr. Emilio R. Vega, the president and CEO of Structural Prestressed Industries Inc., for providing steel strands and steel chucks, and Composite Rigging Southern Spars for providing the EC6 strands, are gratefully acknowledged. All experiments were conducted at the Titan America Structures and Construction Testing Laboratory of the Florida International University. The views and findings reported here are those of the authors alone, and not necessarily the views of sponsoring agency.
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Information & Authors
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Published In
Journal of Composites for Construction
Volume 20 • Issue 1 • February 2016
Copyright
© 2015 American Society of Civil Engineers.
History
Received: Jan 19, 2015
Accepted: May 28, 2015
Published online: Jul 16, 2015
Discussion open until: Dec 16, 2015
Published in print: Feb 1, 2016
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